This article kind of misses the forest for the trees. While I agree with many of the author's points, that's not why the #TwitterMigration failed. It failed because Twitter/Mastodon isn't really a social networking site, and Mastodon didn't provide the same service that Twitter does. At its core, Twitter is about small numbers of (usually famous or important) users communicating with large audiences of followers. #TwitterMigration failed because not enough of those famous and important people moved from Twitter to Mastodon, so the average user had no content they cared to read. Seeing posts from your friends about what they had for dinner last night is all well and good, but the stuff people actually want to see is famous person A throwing shade at famous person B while famous person C talks about the new movie they're in and important organization D posts a warning about severe weather in the area. You don't go to Twitter to have discussions, you go to Twitter to get news and gossip direct from the source.
In contrast, sites like Reddit and kBin/Lemmy are about having group conversations around a topic. Interacting with famous people is neat but not the point. Think of Reddit/kBin/Lemmy as random conversations at a party whereas Twitter/Mastodon is some random person on the corner shouting to a crowd from a soapbox. #RedditMigration has a much better chance of succeeding simply because the purpose of the site is different. As long as enough people move to kBin/Lemmy to have meaningful conversations (aka content), it will have succeeded.